Basal metabolism machine



March 5, 1940. c. v. PERRILL BA SAL METABOLISM MACHINE Filed Dec. 28,1937 m M INVENTOR.

ATTORNEY.

Patented Mar. 5, 1940 UNITED STATES PATENT orr cr.

6 Claims.

My invention relates to improvements in a basal metabolism machine, anair metabolimeter, and it more especially consists of the featuresrecited in the claims. I

The purpose of my invention is to dispense with the complexity and costof existing metabolism equipment in which special oxygen tanks are used.My simplified system is inexpensive, and simple to operate as I onlymake use of free air with its 1 normal oxygen content of 21%. Actualdemonstrations under careful controls have proved the eificacy of mybasal metabolism machines which are available at remote places thatcannot ordinarily be reached and supplied with the regular oxygen tankmachines.

With these and other ends in view I illustrate in the accompanyingdrawing such instances of adaptation as will disclose the broad featuresof my invention without limiting myself to the specific details shownthereon and described herein.

Fig. l is a side elevation of an assembled machine.

Fig. 2 is a diagrammatic sectional elevation of Fig. 1.

Fig. 3 is a diagrammatic top plan View on a level of the fan motor, thetop portions of Fig. 2 being omitted.

Fig. 4 is an enlarged diagrammatic elevation of the recording mechanism.

Fig. 5 is a detached diagrammatic view showing the relation of theinlets and outlets to and from the soda lime chamber in the absence of afan.

In the use of my metabolism machine I may employ whatever alternativesor equivalents of structure that the exigencies of varying conditionsmay demand without departing from the broad spirit of the invention.

The machine may include any desired form of cabinet, supported on asuitable base. The device comprises a large air chamber, a kymograph, aspirometer, a circulating fan, a soda lime container, a mouth-piece andconnecting tubes, and mechanism for recording the changing positions ofthe spirometer bell, on the kymograph drum, all without the use ofoxygen tanks.

On a base I a spirometer chamber or well 2 is supported. This has awater or oil jacket enclosure 3. Below the chamber 2 a fan chamber t ispositioned on the base i and above it there is a soda-lime container 5.The spirometer 2 is' enclosed in a large air chamber 6. Between the airchamber 6 and the spirometer, a vertical tube 2| is secured to the wallsof the air chamber.

On top of the air chamber the kymograph drum 8. is positioned where itis connected to its driving clock 9.

The kymograph drum 8 has its spindle connected to the driving clock 9.The clock is supported from the underside of a removable plate 5 N).This plate covers an opening in the top wall of the air chamber 6. Theclock is isolated at H from'the air chamber by side walls connected toan enclosing bottom. These walls are secured to the underside of the topportion and the side of 10- the air chamber 6.

If desired any standard kymograph movement on a tripod may be used bysimply standing it on the top of the air chamber, though a moredesirable position of the kymograph drum to the recording pen or stylusis secured by my arrangement. The distance between the standard 1 in thetube 2|, on which the recording mechanism is supported and the axis ofthe kymograph drum is maintained at a definite dimension.

The spirometer bell I3 is supported by a cable l2 which passes over agrooved sheave M which has bearing in a bracket I5 that is supported onthe upper end of the standard 'l. The cable I2 is held taut by a leadcounterweight l6. This has up and down movement between two guide barsll that are attached tothe standard 1. To the counterweight Hi, therecording arm H3 is pivoted. At one end this arm carries a recorder 19which may be a stylus or a trough shaped pen. The other end of the arml8 carries an adjustable counterweight 20 adapted to place the recorderunder the desired tension against the drum.

The standard I passes through the tube 2| vertically across the airchamber 6. The fan chamber 4 encloses the fan 22. It is supported on aremovable plate 23 and an air tight gasket so that it can be easilytaken out of the chamber. The leading in wires are also sealed againstair leakage.

The spirometer chamber 2 has an air connection 33 to the large airchamber 6 from which free air is inhaled by the patient through thetubes 3 35 and the flexible tube 28 to the mouthpiece 2d. The flexibletube 28 connects the mouthpiece to the cabinet and a separate flexibletube 25 connects the mouthpiece to the fan chamber 4 through the tube3|.

In case the metabolimeter is to be operated without fan circulation theexhalation tube 25, Fig. 5, connects with a horizontal tube 26 thatpasses through the wall of the air chamber and the wall of the chamber 5in an air tight manner. The tube 26 has a flat rubber valve 21 whichterminates beneath the soda-lime container 5. The inhalation through themouthpiece 24 is over a flexible tube 28 that is connected to a shorttube 29 which passes through the air chamber wall in an air tightmanner. A fiat rubber valve 36 is placed in a down tube that connectsthe spirometer 2 to the short tube 29, as directed by the dotted arrow.The valves 21 and 36 only permit flow in one direction.

During fan operation exhaled air from the mouthpiece 24 passes throughflexible tube 25 and a short tube 3i into the fan chamber 4, from wherethe fan 22, driven by a small six volt motor 32 moves the exhaled airupward through the soda lime in container from where it passes into thespirometer chamber 2. It then descends and enters the air chamber 5through a passageway 33 placed at any desired point. An incandescentlamp may be placed on the base within the air chamber 6 to provide acertain degree of initial heat if desired. The thermometer 3'! isinserted into the air chamber 6 through any desired form of rubber plug.

The modification shown in Fig. 5 is only used when the device isoperated without the fan motor. During inhalation air that has passedthrough the soda-lime container 5 into the spirorneter chamber 2 passesthrough the flat rubber valve 30 into the tube 7.9 and the flexible tube28 to the mouth piece 2 During exhalation the expelled air passesthrough the flexible tube 25, and short tube 25 to the flat rubber valve27 which terminates beneath the soda-lime container 5. The valves 27 and39 serve as ordinary check valves otherwise exhaled air would passthrough tube 28 and tube 29 back into the spirometer chamber 2.

Inhaled air is taken from the air chamber 5 by plural inlets 3Qconnected by a single tube 35, which leads through the casing of the airchamber and is connected to the mouthpiece 24 by flexible tube 28. Thetubes ill, 35 and 36 as they pass through the wall of the air chamberare sealed off to guard against leakage of air. The extra tube 36 leadsfrom the spirometer chamber 2 to the outer air. It is plugged, exceptingwhen a gas analysis is to be made.

I have found that in the use of free air as against conventional oxygenthat the person under observation and taking the test does not manifestany oxygen want. It has been definitely shown that the oxygen tension ofthe air breathed can fall decidedly before any detrimental physiologicalchanges can be noted. Authorities in the field of basal metabolism havefound that the oxygen intake begins to fall only when the oxygenconcentration in the air breathed is 14.8% or lower. It has been foundin tests that have been made that the results of the test in which freeair was used agreed to 1.8% with those in which oxygen was used. The airchamber is of SllffiClGllt capacity to provide the patient with freshair for the entire sixminute period of a test. I have further found thatdeterminations of metabolism on a number of subjects gave results whichvaried by less than two percent irom that obtained under exactly similarconditions with a standard oxygen machine. This slight variation iswithin the requirements of clinical calorimetry.

- The capacity of my metabolism machine is one cubic foot (30 liters).This reduces the total capacity of my machine to a minimum, thusincreasing its compactness. and portability. Any errors of gas volumechanges are kept at a minimum, through the use of these safe dimensions,which were adopted only after extensive researches.

The soda lime container may be easily removed which makes it possible toobtain an accurate measure of the difference between the oxygenconsumption and the carbon dioxide output of the patient breathing intothe soda-lime container.

When this data is used in conjunction with the oxygen consumption rateas measured with the soda lime container, it is possible to calculatedirectly the respiratory quotient of the patient. This is possible onlybecause the capacity of this machine is as great as 30 liters, acapacity not hitherto attained in portable machines. The

oxygen consumption of the patient may be measured with increasedaccuracy because the gas breathed is not abnormally oxygen-rich. Hence,there is no tendency for an excessive oxygen absorption to take placeinto the body circulation, as would ordinarily exist in all conditionsin which anoxernia or a tendency toward cyanosis is present.

The working capacity of the spirometer bell is gauged so as to maintaina ratio of 7% to 100% of the total gas in the metabolimeter. By means ofthis arrangement the subject will exhaust only about '7 of the gas inthe system. By reason of this an automatic check is provided whichprevents any test being carried beyond the safe limits within which themachine is designed. Through my elimination of the necessity for addingoxygen to the free air within the metabolilneter an accuratedetermination of the oxygen consumption of the subject is neverthelesspossible without danger or discomfort due to oxygen want.

By securing the fan motor to a removable plate it is easily removed.plate and all, for adjustment, and repairs or for a quick and easy wayof transforming the machine into a motorless model. The water jacketseal is placed almost entirely within the cabinet. This insurescompactness. rigidity and it equalizes the temperature of the airsurrounding it, thus maintaining a relatively constant temperature. Thesheave supporting tube is supported within the tube that is attached tothe bottom and at the top of the air chamber walls making it very rigid.

For ease in shipping etc., the supporting tube '1 is a separate piece,it passes into a tube 2 I. This tube may project above the chamber andit may have a set screw to hold the tube l and the sheave i l in properalignment with the bell l3 and the counterweight iii of the recordingmechanism. In addition the tube 1 may be supported at different heightsas desired.

To insure that no oil spray or any products emanating from the runningmotor will contaminate the air from the air chamber which the subject isto breathe it is encased in its own housing. Air can be removed throughthe tube 36 for gas analysis while the other tubes are stoppered. Whentubes 33 and 35 are stoppered the metabolimeter may be used in a mannersimilar to the conventional oxygen-using machines. Ordinarily the tube36 remains stoppered and the others remain open. A complete circulationof the air is secured by dividing the tube 35 into two parts, 34, sothat air enters at the far distant corners of the air chamber and thusthe convection currents prevent any stratification of air within thesystem. The electric fan insures a continuous circulation of air whenthe machine is used without Sadd or other types of rubber valves,

by reason of this I eliminate the energy which the subject wouldotherwise have to expend in opening and closing mechanically operatedvalves.

The valves 21 and 36 shown on Fig. are thin 5 rubber flaps united attheir distal tips.

It will be apparent from the description that my machine can beinexpensively constructed, easily assembled, and serviced for repairsetc., conveniently transported and operated in remote places at smallexpense.

What I claim is:

1. In free-air basel metabolism machines a large fixed capacity airstorage chamber with a capacity of approximately 30 liters, aspirometer, a soda-lime container, a mouth-piece, a flexible tubeconnecting the mouthpiece with the air chamber, a connection from thespirometer to the air chamber, a flexible tube connecting the mouthpiece with the soda-lime container through a fan compartment, aconnection from the fan compartment to the spirometer through thesoda-lime container, an air circulating fan in the compartment, anadjustable standard, a sheave on the standard, a kymograph drum and aclock drive therefor, a gravity acting recording mechanism engaging thedrum, and a cable on the sheave connected to the spirometer and therecording mechanism whereby a change in the vertical position of thespirometer bell is transmitted to and recorded on the kymograph.

2. In basal metabolism machines, a largecapacity free-air storagechamber having a capacity of approximately 30 liters, a spirometerconnected to the air chamber, an isolated fan compartment, a fantherein, a soda-lime container connected to and positioned between thefan compartment and the spirometer, a mouth piece, connections therefromto the air chamber and separate connections therefrom to the fancompartment, and means for recording the differences in volume of air inthe system.

3. In basal metabolism machines, a large capacity air storage chamber, asealed off clock chamber and a sealed off fan compartment isolated fromthe air chamber, a spirometer connected to the fan compartment, asoda-lime container contained within the air chamber, a mouth piece,flexible connections therefrom leading separately to the air chamber andthe fan compartment, a kymograph, a driving clock therefor said clocksupported in the clock chamber, a fan in the fan compartment, aconnection from the fan chamher to the soda-lime container, a connectionfrom the latter to the spirometer and from the spirometer to the-storagechamber, and means for recording variations in the volume of air in thevarious connections on the kymograph.

i. A basal free-air metabolism machine comprising a large capacity airchamber, a spirometer within the chamber, a connection therefromcommunicating with the air chamber, a fan compartment connected to thespirometer also within but isolated from the chamber, a mouth piece,sepa rate connections from the mouthpiece to the air chamber and the fancompartment, and means for recording the variable volumes of air passingthrough the mouthpiece without the use of oxygen tanks.

5. A basal free-air metabolism machine comprising a large capacity airchamber, a spirometer within the chamber, a connection therefromcommunicating with the air chamber, a fan compartment connected to thespirometer also within but isolated from the air chamber, a mouthpiece,a separate connection from the mouthpiece to the air chamber suchconnection terminating in a plurality of inlets in the air chamber, aseparate connection from the mouthpiece to the fan compartment, aseparate outlet from the spirometer chamber to the outside of the airchamber adapted for separate gas analysis, and means for recording thevariable directions of air movement through the mouthpiece without theuse of oxygen tanks.

6. A basal free-air metabolism machine comprising a spirometer having awell, a large capacity air chamber, said spirometer well depending intothe air chamber, an upwardly extending air tube within the spirometer, aconnection from the spirometer to the air chamber, a soda lime containerwithin the air tube, a fan chamber beneath the soda lime containerisolated from the air chamber, a removable supporting plate for the fan,a mouthpiece, a connection therefrom terminating in spaced apart areasof the air chamber, another connection from the mouthpiece to the fanchamber, a connection from the fanchamber to the spirometer through thesoda lime container and the air tube, and means for recording thevariable volume of air in the spirometer.

CHARLES V. PERRILL.

